[MDEV-12200] Query Cache Contention Created: 2017-03-07 Updated: 2022-11-01 Resolved: 2022-11-01 |
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| Status: | Closed |
| Project: | MariaDB Server |
| Component/s: | Query Cache |
| Affects Version/s: | 10.0.29-galera |
| Fix Version/s: | N/A |
| Type: | Bug | Priority: | Major |
| Reporter: | Suresh Srinivas | Assignee: | Oleksandr Byelkin |
| Resolution: | Duplicate | Votes: | 0 |
| Labels: | performance | ||
| Environment: |
Operating System CPU: Running HHVM with Wordpress to talk to the database |
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| Issue Links: |
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| Description |
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oss-performance is a Hack language script which controls the operation of nginx, siege, and a specified PHP or HHVM runtime using MariaDB. It performs the following steps: When the Query Cache is enabled, we see very low CPU utilization and in the mariadb shell we see (using show processlist We disabled the Query Cache and are able to saturate the CPU and also doubled the performance. |
| Comments |
| Comment by Elena Stepanova [ 2017-03-08 ] |
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sanja, please take a look. I didn't try to reproduce yet. |
| Comment by Alexander Krizhanovsky (Inactive) [ 2019-04-11 ] |
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The contention is easy to reproduce. I described technical issues and a proposal to rewrite QC in MDEV-18764, but there are opinions to remove QC at all, just like Oracle did this. |
| Comment by Oleksandr Byelkin [ 2019-10-11 ] |
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you can switch it off if you want |